Nanosilver porous material particles and fabricating method thereof

ABSTRACT

Nanosilver porous material particles and method for manufacturing the same are disclosed. The nanosilver porous material particles include nanosilver particles distributed on the surface thereof. First, a nanosilver precursor is dissolved in water and a proper quantity of a fixation agent is added to form a solution. Next, a proper quantity of the porous material particles is added into the solution and that is mixed well to form a suspension. Next, the suspension is allowed to stand for a predetermined period of time, and then the suspension is filtered to separate the porous material particles from the solution. Finally, the resulting porous material particles are baked and dried.

1. FIELD OF INVENTION

This invention relates to a porous material particles, and moreparticularly to a nanosilver porous material particles and themanufacturing method thereof.

2. BACKGROUND OF THE RELATED ART

Activated carbon is porous and has advantages of large BET specificsurface area, high adsorbability, desulfation, debenzoation,deodorization and decoloration properties. Moreover, the activatedcarbon can remove some specific constituents from liquid or gaseousmedium.

Silver has the feature of antibacterial property. Colloidal silver,which includes tiny silver particles with diameter in a range of 10-100nanometers, or nanosilver, developed recently, and is widely applied inmany antiseptic products. For example, the colloidal silver is used asthe antibacterial agent before penicillins were discovered, which cankill many kinds of microbes that are resistant to penicillins. Accordingto recent research reports, nanosilver particles can easily attach withcell membrane or cell wall of a bacterium due to the positive charge onthe surface of silver particle, and easily enter inside the bacteriumand combine with the thiol (—SH) group, which is essential in aerobicmetabolism. Therefore, the nanosilver can disrupt or retard themetabolism of the bacterium and inhibit the bacterium without adverselyharming the host.

The combination of the activated carbon and silver particles providesthe advantages of high adsorbability and high antiseptic ability, andhas been used in products of many fields. The activated carbon andsilver particles provides an excellent inorganic antiseptic without theproblems of drug resistance. However, the silver particles used inactivated carbon with silver content are not nanometric level such thatthe silver particles on surfaces of the activated carbon to havedisadvantage of low efficient bacteriostasis. For enhancing thebacteriostasis, the silver content on the activated carbon is raised,but that also gets a side effect of polluting the environment anddegrading the quality of water due to the escape of the silver on theactivated carbon.

SUMMARY OF THE INVENTION

The present invention is directed to a nanosilver porous materialparticles and a manufacturing method thereof. First, a solution of thenanosilver precursor and a fixation agent are mixed to form a mixture.Next, a proper quantity of porous material particles is added into themixture. The resulting suspension is allowed to stand for apredetermined period of time to allow the nanosilver precursor to adhereon the surface of the porous material particles. Finally, the suspensionis filtered to separate the porous material particles from the solutionand then the resulting porous material particles is baked and dried.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating the manufacturing method of thenanosilver porous material particles according to an embodiment of thisinvention.

FIG. 2A is a picture of the nanosilver porous material particle capturedwith ×10000 magnification according to an embodiment of this invention.

FIG. 2B is a picture of the nanosilver porous material particle capturedwith ×20000 magnification according to an embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the method for manufacturing nanosilver porous materialparticles of this invention is described with reference to FIG. 1.

First, the nanosilver precursor is dissolved in water (step 10). Next,the fixation agent is added into the resulting solution (step 20). Next,a proper quantity of porous material particles is added into theresulting solution (step 30) and the solution is mixed well to form ahomogenous suspension. Next, the suspension is allowed to stand for apredetermined duration of time (step 40). The predetermined duration oftime may be in a range of 0.5 hour to 36 hours and, in the meanwhile,the nanosilver precursor will adhere on the surface of the porousmaterial particles. The suspension is filtered to separate the porousmaterial particles from the solution (step 50). Next, the resultingporous material particles are baked under a temperature ranging from 80°C. to 300° C. for a period of 5 to 24 hours (step 60).

In the present embodiment, examples of the nanosilver precursor includesilver nitrate, silver acetate, silver lactate, silver sulfate, silverphosphate, silver fluoride, silver chloride, silver bromide, silveriodide or composites thereof. The fixation agent may include a weakacid, a weak alkali or composites thereof. Examples of the weak acidinclude glacial acetic acid, and the weak alkali includes ammonia water,such as the 25% ammonia water often seen commercially. Examples of theporous material particles include ceramic, activated carbon, hollowcentered glass ball, solid glass ball, bamboo carbon, coconut shellcarbon, charcoal, Tenax-TA or composites thereof, wherein the activatedcarbon can be powder, particle-pellet, fiber, pillar-shaped particle orhoneycomb-shaped particle and so on.

The better ratio of nanosilver precursor, water, fixation agent and theporous material may be optimized according to actual requirements. In anembodiment, the used weight ratio of the nanosilver precursor to thewater, fixation agent, and the porous material particles ranges from0.025% to 0.5%, from 1.25% to 25% and from 0.05% to 1%, respectively.

The nanosilver porous material particles may be used to deodorize,inhibit bacteria, adsorb gas or liquid, filter and purify gas or liquid,decolorize drug or food, preserve drug or food. Further, the nanosilverporous material particles can be applied in recovery solvent products,catalyst carrier, filter core, conditioner filter net, heater filternet, air filter net, aquarium-related components, fiber cloth, cleanappliances, industrial gas protection equipment or activated carbon maskand so on.

FIG. 2A and FIG. 2B are pictures of the surface of the nanosilver porousactivated carbon captured with 10,000 and 20,000 times magnification,respectively. In pictures, the grey background is the activated carbon,the dark parts are the tiny pores of the activated carbon, and thebright dots on the surface are the silver particles. The magnificationfactors are shown at the bottom of the pictures, where the bar over the1 μm represents 1 micrometer (micrometer, μm=10⁻⁶ meter). From pictures,it can be seen that there are about 80˜200 silver particles in 1 μmarea, indicating that the silver particles are nanometric particles. Thediameter of the silver particles is in a range from 10-999 nanometers(nanometer, nm=10⁻⁹ meter).

Next, the adhering strength of silver particles may be tested by amethod of determining the quantity of silver released from the activatedcarbon. Plasma-coupled atomic spectrum analyzer is used to measure thequantity of silver content in water filtered from a solution immersedthe nanosilver porous activated carbon in different time intervals. Theresult is listed in Table 1, wherein n.d. indicates not detectable andppm means part per million, and the detection limitation of theequipment is 0.01 ppm. The result in Table 1 shows that the filtrate ofthe filter equipment, filled with nanosilver porous activated carbons,does not contain detectable silver content even after the immersingperiod of 7 days, and that demonstrates the considerable adhesivestrength of silver particles on the surface of the activated carbon.

TABLE 1 the detected silver amount of the filtrate of the filterequipment with nanosilver porous activated carbons in an immersingperiod test item unit 1 day 3 days 7 days silver ppm n.d. n.d. n.d.

The BET specific surface area may be tested by using an ASTM D3663-92.ASTM D3663-92 can be used to measure the surface area of activatedcarbon per gram (m²/g). The test includes comparing the surface areas ofthe pure activated carbon and the nanosilver porous activated carbon toevaluate the reduction in the functionality of the activated carboncaused by the coverage of silver particles. Table 2 shows the BETspecific surface area of the pure activated carbon is 926 m²/g and thatof the nanosilver porous activated carbon is 895 m²/g. The reduced areafrom the silver coverage is less than 3.5% to reveal no remarkableeffect.

TABLE 2 nanosilver porous test item unit pure activated carbon activatedcarbon BET specific m²/g 926 895 surface area

Iodine adsorption is used to test the adsorbability of activated carbonfor an aqueous sample. ASTM 4607 is a method to measure the adsorptionof iodine per gram (mg/g) of activated carbon and nanosilver porousactivated carbon. Table 3 shows iodine adsorption of pure activatedcarbon and nanosilver porous activated carbon are 1003 mg/g and 1040mg/g, respectively. It is obvious that the iodine adsorption is notreduced in nanosilver porous activated carbon.

TABLE 3 Nanosilver porous test item unit pure activated carbon activatedcarbon iodine mg/g 1003 1040

Although this invention has been explained in relation to its preferredembodiment, it should be understood that modifications and variation canbe made without departing the spirit and scope of the invention asclaimed.

1. A nanosilver porous material particle, comprising: a porous material;and a plurality of nanosilver particles homogeneously distributed on asurface of said porous material.
 2. The nanosilver porous materialparticle according to claim 1, wherein said porous material is selectedfrom the group consisting of ceramic, activated carbon, hollow centeredglass ball, solid glass ball, bamboo carbon, coconut shell carbon,charcoal, Tenax-TA or composites thereof.
 3. The nanosilver porousmaterial particle according to claim 2, wherein said activated carbonincludes powder, particle-pellets, fibers, pillar-shaped orhoneycomb-shaped particles.
 4. A method of manufacturing nanosilverporous material particles, comprising: dissolving a nanosilver precursorin water and adding a fixation agent to form a mixture; adding a porousmaterial into said mixture and stirring to form a suspension; standingsaid suspension for a predetermined duration of time; filtering saidsuspension to separate nanosilver porous material particles; and bakingsaid nanosilver porous material particles.
 5. The method ofmanufacturing nanosilver porous material particles according to claim 4,wherein a weight ratio of said nanosilver precursor to said water rangesfrom 0.025% to 0.5%.
 6. The method of manufacturing nanosilver porousmaterial particles according to claim 4, wherein a weight ratio of saidnanosilver precursor to said fixation agent ranges from 1.25% to 25%. 7.The method of manufacturing nanosilver porous material particlesaccording to claim 4, wherein a weight ratio of said nanosilverprecursor to said porous material ranges from 0.05% to 1%.
 8. The methodof manufacturing nanosilver porous material particles according to claim4, wherein said nanosilver precursor is selected from the groupconsisting of silver nitrate, silver acetate, silver lactate, silversulfate, silver phosphate, silver fluoride, silver chloride, silverbromide, silver iodide or a composite thereof.
 9. The method ofmanufacturing nanosilver porous material particles according to claim 4,wherein said fixation agent includes a weak acid, a weak alkali or acomposite thereof.
 10. The method of manufacturing nanosilver porousmaterial particles according to claim 9, wherein, said weak acidincludes glacial acetic acid.
 11. The method of manufacturing nanosilverporous material particles according to claim 9, wherein said weak alkaliincludes ammonia water.
 12. The method of manufacturing nanosilverporous material particles according to claim 9, wherein said compositeincludes a mixture of glacial acetic acid and ammonia water.
 13. Themethod of manufacturing nanosilver porous material particles accordingto claim 4, wherein said predetermined duration of time ranges from 0.5hour to 36 hours.
 14. The method of manufacturing nanosilver porousmaterial particles according to claim 4, wherein the step of baking isperformed at a temperature in a range of 80 to 300° C.
 15. The method ofmanufacturing nanosilver porous material particles according to claim 4,wherein the step of baking is performed for a duration of 5 to 24 hours.16. The method of manufacturing nanosilver porous material particlesaccording to claim 4, wherein said porous material is selected from thegroup consisting of ceramic, activated carbon, hollow centered glassball, solid glass ball, bamboo carbon, coconut shell carbon, charcoal,Tenax-TA or a composite thereof.
 17. The method of manufacturingnanosilver porous material particles according to claim 16, wherein saidactivated carbon includes powder, particle-pellets, fibers,pillar-shaped or honeycomb-shaped particles.